


Doctor's Orders

by StrongBrush1



Category: Undertale (Video Game)
Genre: Dom/sub Play, F/F, First Time, Futanari, Oral Sex, Vaginal Sex
Language: English
Status: Completed
Published: 2018-09-15
Updated: 2018-09-15
Packaged: 2019-07-12 17:23:12
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,492
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15999860
Author URL: https://archiveofourown.org/users/StrongBrush1/pseuds/StrongBrush1
Summary: Undyne gets invited over to Alphys' apartment for a surprise. Little does Undyne know that she's going to be in for quite an experience.Note: This story takes place after the "True Ending" of Undertale where Frisk doesn't kill anybody.





	Doctor's Orders

**Author's Note:**

> Since today marks the third anniversary of Undertale's release on PC, I thought maybe I'd release this story I've been sitting on for a while. I actually wrote this at the end of August but I wasn't entirely sure if I should release it. Well, in any case, here it is now. Enjoy some fish-on-dinosaur action.

The doctor probably had a new anime she wanted to show her. That’s the only reason Undyne can think of why Alphys would invite her over specifically using the words ‘I’ve got a surprise I want to show you.’ The Doctor’s new home on the surface was not quite as big and foreboding as her old home in the Royal Lab, and Undyne was perfectly okay with that. Honestly, the thought of even going into the Royal Lab was a terrifying prospect for Undyne. She had heard… bad things from Frisk.

Anyhow, Undyne had made her way up to the Doctor’s apartment. The outside of the door was pretty unassuming, so she often found herself knocking on a completely different door by accident. This would usually cause the person on the other side to react with horror, and then confusion as she explained that she forgot where Apartment 0915 was, before calmly apologizing and bidding her good day. She didn’t blame the humans for this. After all, when you see a tall, sharp-toothed fish woman at your door, you’re bound to have some concerns.

Knocking on the door to 0915, Undyne announced her presence to Alphys. “C-come in,” said Alphys, trying her best to sound seductive. Undyne stepped inside and immediately closed the door behind her. She knew that Alphys had a thing about privacy and didn’t want her to get upset. The messy, poster-covered dinosaur’s den felt, oddly enough, welcoming to Undyne.

Sitting at a swivel chair over by her computer was Dr. Alphys, who had been in the middle of playing a visual novel. Undyne could somehow tell, even through the solid back of the computer chair that Alphys was sitting in, that something felt… different about her today. She didn’t look as… slouchy, or timid. She still seemed shy, yes, but less so.

“Hey, Alphys. What’s that game you’re playing?”

Alphys suddenly got excited. “Oh, it’s a visual novel about this girl who had captures the hearts of three different knights and has to choose between them, in the aftermath of a deadly war that left her kingdom decimated. It’s really engaging but I don’t know whether to go for Lance or Percy, I mean there’s also Robin but I don’t really like him that much…” Alphys suddenly realized she was rambling again. “Oh. You, uh… You probably aren’t that interested are you?”

Undyne steeled herself and got straight to the point. “Don’t worry. You can tell me all about it. I mean you did invite me over to show it off, didn’t you?”  
“Um…”  
“So tell me, what are these two guys like. Is Lance like, a brave warrior who takes no prisoners and kicks demon ass?”  
“That’s… not what I called you here for.”  
“Oh. Well then, what did you call me over for?”

Alphys blushed. She started to turn in her computer chair, but suddenly hesitated, as if she had realized something that she didn’t want Undyne to see. “Well, I’d been watching some... special anime… actually… it was hentai. And it got me thinking… maybe, you know...”  
“...Maybe what? Where are you going with this?”  
“I, um… I was thinking to myself, maybe, I…”

Alphys’ yellow face was now bright red. She clearly had something on her mind. She started to turn, then turned back, once, maybe twice. Undyne patiently stood by and waited for Alphys to finish. Finally, with a sudden, quick whirl in the computer chair, Alphys now faced herself towards Undyne. She was completely naked.

Undyne took a glance at Alphys, who in spite of revealing her nudity, was burying her face in her claws and crossing her legs. Her stature was small, stout, and somewhat flabby. After a quick once-over, Undyne noticed that Alphys’ bare breasts were a bit larger than they normally were. Is that why she was so embarrassed?

Undyne took a quick breath. “Is that what you wanted to show me? You got a boob job? That’s cool. They look… nice.” She expected Alphys to shyly reply with something to the extent of ‘thank you’ or ‘you’re too kind’ or at the most extreme, ‘I want to have sex, if that’s alright’. Undyne and Alphys had been something of a couple for some time now, so it made sense that perhaps she wanted to take things to the next level.

“I… I did make my boobs bigger, but that’s… that’s not…” Alphys bit her lip, still unable to look at Undyne. “That’s not all I did.”  
Undyne was intrigued. “What else did you do?”  
Alphys was somehow blushing harder than before. “Promise me you won’t hate me.”  
“I don’t! I won’t! Just tell me what this is about!”

Just as suddenly as she had turned around, Alphys uncrossed her legs and blurted out: “I GAVE MYSELF A PENIS BECAUSE I REALLY WANT TO HAVE SEX WITH YOU PLEASE DON’T HATE ME!”

Undyne needed a moment to register this statement. Looking down, sure enough, Alphys had given herself a rather sizeable penis, about eight inches in length from the look of it. Suddenly, it made sense why she had mentioned hentai, and why she had been so hesitant to turn around before. What didn’t make sense was how she had kept that large thing tucked away between her legs, and why, if she was going to go through the trouble of giving herself a penis, wasn’t going to act like she had one.

Undyne’s face scrunched up slightly. Not because she was averse to the idea of being penetrated by her girlfriend, but because she once again had to step in and teach Alphys a quick lesson about her unique brand of social etiquette. “So that’s it? You want to fuck me?”

Alphys suddenly looked ashamed of herself. “Y-yeah…”  
“Well then why don’t you start acting like it?”  
Alphys was mildly afraid. “...Huh?”  
“You gave yourself a dick and now, when you’re so close to spearing me, you’re gonna get soft on me? COME ON! You’re better than that, damn it!”  
“But... I-”  
“NO BUTS! WITH THE SOLE EXCLUSION BEING MY BUTT!”  
Alphys kept her mouth shut. She was now in listening mode.

“You started this bit, now commit to it! Tell me to turn around and bend over!”  
“T-turn around, and… and…”  
“Go on! Tell me to turn around and say it like you mean it!”  
Alphys took a deep breath. She managed to curtly say: “Turn around.”  
Alphys did what she was told. “Yes, mistress! Now tell me to bend over.”  
Alphys couldn’t work up the courage. “B-bend… over.”  
“I can’t hear you!”  
Alphys tried again. “Bend over.”  
“LOUDER!”

Alphys felt something boiling up inside her… something she hadn’t felt in quite a while: anger. Actual, legitimate, anger. “I SAID BEND OVER, BITCH!” Alphys slapped her mouth shut, shocked at the language she had just used. Undyne took notice of this.

“Don’t get polite on me now! Once you get into it, you have to commit! You called me bitch, so I’m your bitch!” Undyne bent over, showing off her shapely behind. “Now, then. Tell your bitch what you want her to do!”

Alphys was hesitant, but managed to find her place of rage and return to it. “Clothes.”  
“What about my clothes, mistress?”  
“Clothes, off. NOW.”

“Yes, mistress!” Undyne took off her black tank top, exposing her comparatively small boobs. After throwing the tank top away, Undyne removed her jeans and panties as well. She was now, for all intents and purposes, naked. “What else can your bitch do for you?”

Alphys decided to have a little fun. “Dance.”  
Undyne looked confused. “Excuse me?”  
“I said DANCE, bitch. I want to see you sweating. And put your ass into it!”

Undyne was confused, but she complied. “Yes, mistress.” Undyne started grooving to a rhythm that was playing in her mind, wildly spinning and shaking her ass as best she could in the limited floor space. Alphys smiled and started masturbating. She couldn’t believe Undyne was actually doing what she said.

Eventually, after two minutes of dancing, Undyne started to feel winded. She slowed down slightly, trying to catch her breath.  
Alphys was still masturbating, still high on rage. “Did I say you could STOP, bitch?”  
Undyne was taken aback by this outburst, but she continued dancing. “I think... you’re getting the hang of this dom thing!”

Alphys stopped masturbating and decided to briefly have mercy on Undyne, who seemed like she was ready to collapse. “Okay, stop dancing.”  
“What was that?” Undyne said, encouragingly.  
Alphys returned to being her dom self. “Stop dancing, bitch!”  
Undyne stopped and leaned over for a moment to catch her breath. She was unusually tired.  
“Now, look at me.” Undyne complied. “You see this cock?”  
Undyne smiled. “Yes, mistress.”  
“I want you to get on your knees and suck it.”  
Undyne got down on all fours and began to suck Alphys off. The feelings of pleasure suddenly overwhelmed Alphys, who eventually could not contain her own feelings of lust. Undyne noticed this and stopped sucking for a moment.

“You’re not seriously going to just give up that easily, are you?”  
“What? I… I thought I was doing well.”  
“You were! But then you got distracted by something you weren’t even participating in! I stopped sucking your dick ten seconds ago! A real dominatrix would have smacked me so hard it’d leave a mark for months, but you didn’t even raise your voice at me. Are you really committed to this bit or not?”

Alphys hesitated. Being forceful wasn’t really in her nature, but at the same time, hse was enjoying the roleplay and Undyne was too.  
“I said, are you committed to this bit or NOT?”  
“I am.”  
“What was that?”  
“I am!”  
“Then ACT like it!”  
Alphys, despite the enormous pleasure she was feeling, found her rage place again. “I don’t recall giving you permission to speak, BITCH!”  
“THAT’S more like it!  
“KEEP SUCKING!”

Undyne went back to fellating Alphys, who despite her pleasure was trying to keep herself in charge of the situation. After about thirty more seconds, Alphys felt an ejaculation fast approaching.  
“I’m- i’m about to cum! I’m gonna cum!”  
Undyne gestured as if to say: “Go ahead, tell me what to do now!”  
“I- I want you- to- to- SWALLOW IT!” Alphys came hard down Undyne’s throat. Undyne, without hesitation, drank every last drop. Once the load was swallowed, Alphys slipped her cock out of Undyne’s mouth.

“Holy shit. That was pretty good for a first time as dom.”  
Alphys blushed. “Thanks. S-sorry about calling you bitch.”  
“Don’t worry about it. You were in the zone. Besides, I don’t mind. I kinda like being your bitch.”  
Alphys smiled and suddenly got an idea. “Well, don’t act like it’s over yet. After all, someone didn’t get to cum.”  
“Alphys, it’s fine. I really don’t-”  
“Listen, bitch!” Both Undyne and Alphys were caught off guard by the unprovoked outburst. Alphys continued, albeit more politely. “I… I am your mistress. You are my bitch. Your body is my... uh… plaything! I get to decide when you’ve had enough, alright?”  
Undyne was liking this new, domineering Alphys. “Yes mistress.”  
“Say it… say it like you mean it!”  
“YES, mistress!” Undyne shouted happily.  
“Now get on your back and spread those legs, bitch!”

Undyne threw herself back onto Alphys’ bed. She was really about to be speared by her girlfriend. This was like a dream come true. Alphys quickly got up, walked over and stuck her cock directly into Undyne’s pussy. The fish-girl’s poor hymen never stood a chance against the monster cock which was now thrusting in and out of her mercilessly. It hurt. But it felt so good.  
Undyne was moaning with pleasure. “Oh, mistress… Oh… yes! YES! YES MISTRESS!”

Alphys wasn’t done yet. Despite her thoughts screaming out ‘what am I doing?!’, she reeled back and smacked Undyne square on the ass. Undyne let out a scream of pleasure. “THAT was for talking out of turn!”  
“YES! PUNISH ME!”  
Alphys raised another claw, and smacked the same spot again. After this, she started smacking the other cheek, and then a second time, then she started alternating between the buttocks like she was playing bongos.

Undyne finally couldn’t last any longer. She came, and came HARD, with a scream of combined pain and pleasure. Alphys, shocked at the capacity of her own dominance, had little time to react before she came as well.  
“Fuuuucck me that was amazing, Alphys!”

Alphys pulled out and ran back to her computer chair, covering her face in shame. “I’m so sorry I’m so sorry I’m so so so sorry I should have put on a condom oh god now you’re gonna get pregnant-”

Undyne noticed Alphy’s sudden change of heart. She really seemed upset at the things she had done. Normally, the course of action now would be to berate her for dropping character so easily, but she figured it might be better at this point to change tactics. The good part was over with anyhow. “Alphys.”  
“Ohhh…”  
“It’s okay. You were great. I really mean it.”  
“Y-you do?”  
“Look, even if I do get knocked up from this, so what? I don’t mind “  
“Really?”  
“You know what I like about you? You challenge me.”  
“I… what?”  
“Every day, whether you realize it or not, you and I are challenging each other to be a better person. Stronger. More confident. But also more relaxed, more open. You may not realize it, but, in a way, we’re both better off having each other near.  
“I suppose… that makes sense.”

“Flash back to our first date. You think you would have had the nerve to give yourself a dick back then?”  
“No. No I wouldn’t.”  
“Just like I wouldn’t have had the guts to be the one on bottom. You know, there’s more to you than your anime obsession. Underneath those big boobs, you’ve got a big heart.”  
Alphys smiled before realizing something. “Oh shoot! You never got to play with my new big boobs!  
Undyne smiled and put her pants back on. “Maybe some other time. I should be going. Night Alphys.”  
Undyne picked up her shirt and made her way over to the door. Alphys called after her. “Undyne, wait!”  
Undyne now had her shirt back on. “Yeah?”  
“Next time we do this… you want to switch places?”  
“If that’s what you want, then okay.”  
“Oh,one more thing... You can take your time closing the door.”  
Undyne smiled. “You got it. See you later… mistress.”  
Alphys sheepishly waved goodbye. “Bye… bitch.”

With a quick, warm chuckle, Undyne was now gone. Alphys, turning back to the computer, resumed her game. She was now being given a choice: flee the land with Percy, or stay and defend the remainder of the kingdom with Lance. After a moment’s consideration, she decided to stay with Lance. After all, there was just something about a spear-carrying knight...


End file.
